In an online application, data architecture provides the most information about the transaction audit trail, as it describes how data are created, stored, processed, accessed and exchanged among different components of the application. Data architecture includes data models, schemas, dictionaries, metadata, standards and policies that define the structure, quality, integrity, security and governance of data. Data architecture can help the IS auditor to trace the origin, flow, transformation and destination of data in an online transaction, and to identify the key data elements, attributes and relationships that are relevant for audit purposes. A system/process flowchart is a graphical representation of the sequence of steps or activities that are performed by a system or process. A system/process flowchart can provide some information about the transaction audit trail, but it is not as detailed or comprehensive as data architecture. A system/process flowchart shows the inputs, outputs, decisions and actions of a system or process, but it does not show the data elements, attributes and relationships that are involved in each step or activity. A file layout is a specification of the format and structure of a data file. A file layout can provide some information about the transaction audit trail, but it is not as detailed or comprehensive as data architecture. A file layout shows the fields, types, lengths and positions of data in a file, but it does not show the origin, flow, transformation and destination of data in an online transaction. Source code documentation is a description of the logic, functionality and purpose of a program or module written in a programming language. Source code documentation can provide some information about the transaction audit trail, but it is not as detailed or comprehensive as data architecture. Source code documentation shows the instructions, variables and parameters that are used to perform calculations and operations on data, but it does not show the data elements, attributes and relationships that are involved in each instruction or operation. References: CISA Review Manual (Digital Version) 1, Chapter 4: Information Systems Operations and Business Resilience, Section 4.2: Data Administration Practices.
